Enkelad (mjesec)

Enkelad (Enceladus) je prirodni Saturnov satelit kojeg je 1789. otkrio astronom William Herschel. Ime je dobio po gigantu Enkeladu iz starogrčke mitologije. Ovaj satelit ima drugo ime Saturn II.

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Enkelad

Enceladus snimljen orbiterom Cassini, oktobar 2015.[a]
Discovery
Discovered by	William Herschel
Designations
Designation	Saturn II
Imenovan po	Ἐγκέλαδος Egkelados
Adjectives	Enceladean /ɛnsəˈleɪdiən/[1][2]
Orbital characteristics
Semi-major axis	7005237948000000000♠237.948 km[3]
Orbital period (sidereal)	7006137021800000000♠1,370218 d[3]
Inclination	0.009° (to Saturn's equator)[3]
Physical characteristics
Mean radius	7003252100000000000♠252,1±0,2 km[4][5] (7002395000000000000♠0,0395 Earths, 7003145100000000000♠0,1451 Moons)
Surface gravity	1.134 m/s2 (7002116000000000000♠0,0116 g)
Moment of inertia factor	7003330500000000000♠0,3305±0,0025[6]
Escape velocity	2.391 km/s (860.4 km/h)[3]
Synodic rotation period	Sinhrona
Axial tilt	0
Albedo	7003137500000000000♠1,375±0,008 (geometrijski na 550 nm)[7] or 7001810000000000000♠0,81±0,04 (Bond)[8]
Surface temp. min mean max Kelvin[9] 32.9 K 75 K 145 K Celsius −240 °C −198 °C −128 °C
Apparent magnitude	11.7[10]
Atmosphere
Surface pressure	Trace, significant spatial variability[11][12]
Composition by volume	91% vode pare 4% nitrogen 3.2% ugljen-dioksid 1.7% metan[13]

Karakteristike

Enkelad obilazi Saturn svakih 32 h 53 m 7 s, ima prosječni prečnik od 498,9 km i masu od 8,6×10¹⁹ kg. Prosječna gustoća Enkelada iznosi 1,3 g/cm³. Mjerenja obavljena od strane svemirske letjelice Cassini-Huygens ookazala su da je ovaj satelit napravljen većinom od leda, vode i možda male količine kamena i metala.

Početkom 2006. NASA-ina letjelica Cassini snimila je erupcije gejzira na površini, vjerovatno sastavljene i od tekuće vode.

Reference

1. Freitas, R. A. (1983). "Terraforming Mars and Venus Using Machine Self-Replicating Systems (SRS)". Journal of the British Interplanetary Society. 36: 139. Bibcode:1983JBIS...36..139F.
2. Postberg et al. "Plume and surface composition of Enceladus", p. 129–130, 148, 156; Lunine et al. "Future Exploration of Enceladus and Other Saturnian Moons", p. 454; in Schenk et al., eds. (2018) Enceladus and the Icy Moons of Saturn
6. McKinnon, W. B. (2015). "Effect of Enceladus's rapid synchronous spin on interpretation of Cassini gravity". Geophysical Research Letters. 42 (7): 2137–2143. Bibcode:2015GeoRL..42.2137M. doi:10.1002/2015GL063384.
9. Spencer, John R.; Pearl, J. C.; et al. (2006). "Cassini Encounters Enceladus: Background and the Discovery of a South Polar Hot Spot". Science. 311 (5766): 1401–5. Bibcode:2006Sci...311.1401S. doi:10.1126/science.1121661. PMID 16527965. S2CID 44788825.
11. Dougherty, M. K.; Khurana, K. K.; et al. (2006). "Identification of a Dynamic Atmosphere at Enceladus with the Cassini Magnetometer". Science. 311 (5766): 1406–9. Bibcode:2006Sci...311.1406D. doi:10.1126/science.1120985. PMID 16527966. S2CID 42050327.
12. Hansen, Candice J.; Esposito, L.; et al. (2006). "Enceladus' Water Vapor Plume". Science. 311 (5766): 1422–5. Bibcode:2006Sci...311.1422H. doi:10.1126/science.1121254. PMID 16527971. S2CID 2954801.
13. Waite, Jack Hunter Jr.; Combi, M. R.; et al. (2006). "Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure". Science. 311 (5766): 1419–22. Bibcode:2006Sci...311.1419W. doi:10.1126/science.1121290. PMID 16527970. S2CID 3032849.

• Brown, Robert H. (2006). "Composition and Physical Properties of Enceladus' Surface". Science. 311 (5766): 1425–1428. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Castillo, Julie C. (2005). "26Al in the Saturnian System - New Interior Models for the Saturnian satellites". Eos Trans. AGU. 82 (52): Fall Meet. Suppl. Abstract P32A-01. Arhivirano s originala, 30. 9. 2007. Pristupljeno 3. 7. 2013. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Castillo, J. C. (2006). "A New Understanding of the Internal Evolution of Saturnian Icy Satellites from Cassini Observations" (PDF). LPSC. XXXVII. Abstract 2200. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Dougherty, M. K. (2006). "Identification of a Dynamic Atmosphere at Enceladus with the Cassini Magnetometer". Science. 311 (5766): 1406–1409. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Hansen, Candice J. (2006). "Enceladus' Water Vapor Plume". Science. 311 (5766): 1422–1425. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Matson, D.L. (2006). "Enceladus' Interior and Geysers - Possibility for Hydrothermal Geometry and N₂ Production" (PDF). LPSC. XXXVII. Abstract 2219. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Pappalardo, R.T. (2006). "Diapir-Induced Reorientation of Enceladus" (PDF). LPSC. XXXVII. Abstract 2113. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Porco, C.C. (2006). "Cassini Observes the Active South Pole of Enceladus". Science. 311 (5766): 1393–1401. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Rathbun, Julie A. (2005). "Enceladus' global geology as seen by Cassini ISS". Eos Trans. AGU. 82 (52): Fall Meet. Suppl. Abstract P32A-03. Arhivirano s originala, 4. 4. 2008. Pristupljeno 3. 7. 2013. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Rothery, David A. (1999). Satellites of the Outer Planets: Worlds in their own right. Oxford University Press. ISBN 0-19-512555-X.
• Spahn, Frank (2006). "Cassini Dust Measurements at Enceladus and Implications for the Origin of the E Ring". Science. 311 (5766): 1416–1418. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Spencer, J. R. (2006). "Cassini Encounters Enceladus: Background and the Discovery of a South Polar Hot Spot". Science. 311 (5766): 1401–1405. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Turtle, Elizabeth et al. Enceladus, Curiouser and Curiouser: Observations by Cassini's Imaging Science Subsystem. Cassini CHARM Telecon. 28 April 2005. (Adobe Acrobat file).
• Verbiscer, Anne (2005). "The opposition surge of Enceladus: HST observations 338-1022 nm". Icarus. 173: 66–83. doi:10.1016/j.icarus.2004.05.001. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)
• Waite Jr., J. Hunter (2006). "Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure". Science. 311 (5766): 1419–1422. Nepoznati parametar |coauthors= zanemaren (prijedlog zamjene: |author=) (pomoć)

Vanjski linkovi

• Astronomska sekcija Fizikalnog društva Split - Encelad, Saturnov satelit
• NASA - letjelica Cassini snimila vodu na Enceladusu Arhivirano 24. 1. 2005. na Wayback Machine